The House approved legislation Tuesday that would ban abortions starting at 20 weeks of pregnancy, the most sweeping abortion restriction to pass any chamber of Congress in a decade. The vote was 228 to 196.

While the measure is unlikely to become law — it faces opposition in the Senate and a White House veto threat — it could reverberate politically over the next year and a half, as both Republicans and Democrats appeal to voters in this year’s special elections and the 2014 midterms.

The move was noteworthy in that the pro-life movement, utilizing the same strategy it employed in the partial-birth abortion fight, is moving cautiously to find ground where there is wide support, indeed revulsion, against a category of abortions. Speaker John Boehner (R-Ohio) acknowledged as much in a written statement, which read in part: “The recent conviction of Kermit Gosnell shed the light of intense public scrutiny on the gruesome practice of late term abortion. This bill, which extends protection of unborn babies beyond the 20-week mark, is the most significant pro-life legislation to come before Congress since enactment of the ban on partial-birth abortions.”

On one hand the bill is not an outlier. All but about a dozen states have laws banning abortions beyond viability. However, throughout the country the exception for life or health of the mother has created a giant loophole that permits abortion virtually on demand.

The House bill by contrast would make exceptions for “woman whose life is endangered by a physical disorder, physical illness, or physical injury, including a life-endangering physical condition caused by or arising from the pregnancy itself, but not including psychological or emotional conditions.” Thus, failure to protect the health of the mother raises a Constitutional red flag. (A more interesting test would be to allow an exception for health of the mother, but only from serious physical harm.)

The House bill would also make an exception for rape or incest in the case of a minor, if the incident was previously reported.

The least controversial part of the measure is the 20-week limitation. The Supreme Court has written in terms of viability, so it stands to reason that, as the point of viability is moved back because of science, the court would acknowledge as such in its jurisprudence. But the exceptions are more difficult. The ability to secure an abortion whenever a woman can claim her emotional health is at risk is the crux of the abortion-on-demand culture we have created. (Interestingly, European countries are more restrictive both as to the reasons and time period in which abortion is available.)

As long as the Supreme Court holds to the abortion ruling precedent, legislative variations on abortion restrictions (e.g. to more strictly define health care of the mother) is near impossible. This is the legacy of jurisprudence that moved so quickly that even Justice Ruth Bader Ginsburg has found it unwise and has preempted the issue. In passing the bill, the House has reopened that debate, which is the last thing pro-choice groups want. The prospect that the public, in the wake of Gosnell and this bill, would come to grips with the nature of late-term abortion and its availability virtually for any woman who wants one for any reason is the last thing “pro-choice” groups want.